Clinical research on loss of resistance technique in fascia iliaca compartment block

This study aims to investigate the positioning accuracy and effectiveness of the loss of resistance technique (LOR) in fascia iliaca compartment block (FICB). A total of 175 patients prepared for hip surgery were enrolled; the injection needle was inserted at the centrolateral one-third point of the junction of the anterosuperior iliac spine and external pubic angle, 2 cm parallel to the tail end; after sensing a feeling of "breaking through" twice, 30 mL 0.5% ropivacaine was injected, and its spread was assessed by ultrasound-guidance. The patients were divided into three groups according to needling positions: group A: accurate, group B: too shallow (above the fascia iliac), and group C: too deep (inside the iliopsoas). The sensation blocks of the femoral, lateral femoral cutaneous, and obturator nerves were recorded 20 min after the injection. As observed under ultrasound, the positioning accuracy rate of LOR inside the FIC was 56.6%. The success rate of FICB using LOR was 91.4% 20 min later, and the complete block rate was 68.0%. The successful and complete block rates in group A were significantly higher than those in groups B and C (P < 0.001). The key for successful and complete FICB was accurate injection of the medicine into the FIC, but traditional LOR showed unsatisfactory accuracy when positioning within the FIC.